Hand-held torches and lighters are intended to be used only by one hand, the hand that holds the device. However, the added necessity of safety interlocks to prevent unwanted activation or ignition adds yet one more step, releasing the interlock, to operation of the device, in addition to holding, aiming and igniting. Often, such interlocks or safety latches require pressure or movement that is entirely separate from the movement used to ignite the flame or to hold the device, to the point of needing a separate finger or even a second hand in order to activate the torch or lighter.
Attempts to make release of the interlock proximal to the operation of the ignitor are still relatively clumsy, requiring compound motions of the actuating finger, such as sliding an element in a way that makes it harder to apply force or movement to the actual fuel valve and/or ignitor. In frustration, the typical user will simply interrupt their activity to again use both hands (if possible) to use the torch or lighter.
However, interlocks which are easier to use may also be too easy to defeat, and thus ineffective. If the lighter interlock is defeated by obvious or gross movements, then the torch or lighter may accidentally or too easily light. If the underlying application is to prevent use by children, some skill should be required, yet not overly interfere with intentional adult operation.